Indexable cutting insert having two cutting portions located in diagonally opposite quadrants and two lower abutment elements, and cutting tool therefor

ABSTRACT

An indexable cutting insert has a central mounting portion and two cutting portions. The central mounting portion has opposing upper and lower surfaces. The lower surface has two abutment elements associated therewith, each abutment element having two diverging abutment surfaces forming two abutment angles. The two cutting portions extend away from the central mounting portion, have distal cutting edges, and are entirely located in diagonally opposite imaginary quadrants of four quadrants defined by two mutually perpendicular quadrant planes. Two abutment bisector planes bisecting the two abutment angles and one of the quadrant planes are parallel or coincident. In a top view, the two cutting portions extend away from the central mounting portion in opposite directions. Two cutting bisector lines parallel to the two directions and bisecting the two cutting edges are mutually offset. A cutting tool has an insert holder and the cutting insert removably retained therein.

FIELD OF THE INVENTION

The present invention relates to an indexable cutting insert having twocutting portions located in diagonally opposite quadrants and twoabutment elements, and a cutting tool having such cutting insert, foruse in metal cutting processes in general, and for grooving operationsin a limited working space in particular.

BACKGROUND OF THE INVENTION

Within the field of cutting tools used in grooving operations in alimited working space, there are some examples of a cutting insertshaving two cutting portions located in diagonally opposite quadrants.

U.S. Pat. No. 6,582,163 discloses a tool for chip removing machiningincludes a holder and a cutting insert removably mounted therein. Theinsert includes a shaft having opposite ends and defining a firstlongitudinal center line. A cutting head projects integrally from atleast one end of the shaft. The cutting head includes a cutting edgeforming an angle of 45 degrees with the first longitudinal center line.Alternatively, or additionally, the cutting head defines a secondlongitudinal center line forming an angle of 45 degrees with the firstlongitudinal center line.

U.S. Pat. No. 8,449,225 discloses a metal cutting tool having an insertholder and a cutting insert releasably secured therein. The insertholder has upper and lower blocks and upper and lower jaws, each jawprojects from the front end of each respective block. The cutting toolhas a cutting portion support projecting transversely from the front endof the lower clamp at an angle α. The cutting insert has a shaft and afirst cutting portion projecting transversely from the shaft at theangle α. The cutting insert has non-planar abutment surfaces formed tomate with corresponding, non-planar support surfaces located on thelower and upper jaws and on the cutting portion support.

It is an object of the present invention to provide an improved cuttinginsert.

It is also an object of the present invention to provide an improvedcutting tool, having the cutting insert removably secured in an insertholder with a high level of stability.

It is a further object of the present invention to provide an improvedcutting tool, in which the insert holder is manufactured efficiently andcost-effectively.

It is yet a further object of the present invention to provide animproved cutting tool, suitable for cutting operations in which there islimited access to a rotating workpiece.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided an indexablecutting insert, comprising:

a central mounting portion and first and second cutting portions,

-   -   the central mounting portion having opposing upper and lower        surfaces, an interconnecting peripheral side surface, and an        insert axis passing through the upper and lower surfaces        defining an upward-to-downward direction,        -   the upper surface facing in the upward direction,        -   the lower surface facing in the downward direction and            having spaced apart first and second male and/or female            abutment elements associated therewith,            -   the first abutment element having diverging left and                right first abutment surfaces transverse to the lower                surface, which in a cross-section taken in a first                horizontal plane perpendicular to the insert axis and                intersecting the first and second abutment elements has                left and right first imaginary straight abutment lines                tangential to the left and right first abutment surfaces                forming a first local abutment angle, and a first                abutment bisector plane parallel to or containing the                insert axis bisects the first local abutment angle,            -   the second abutment element having diverging left and                right second abutment surfaces transverse to the lower                surface, which in a cross-section taken in the first                horizontal plane has left and right second imaginary                straight abutment lines tangential to the left and right                second abutment surfaces forming a second local abutment                angle, and a second abutment bisector plane parallel to                or containing the insert axis bisects the second local                abutment angle,        -   the first and second cutting portions extending away from            the central mounting portion and having distal first and            second major cutting edges, respectively, and the first and            second cutting portions being entirely located in diagonally            opposite imaginary quadrants of four imaginary quadrants            defined by mutually perpendicular first and second quadrant            planes containing the insert axis,            -   each cutting portion having a rake surface adjacent to                its respective major cutting edge facing in the upward                direction,

wherein:

the first and second abutment bisector planes and the first quadrantplane are parallel or coincident,

and wherein in a top view of the cutting insert:

the first and second cutting portions extend away from the centralmounting portion in opposite first and second directions, respectively,

first and second cutting bisector lines parallel to the first and seconddirections bisect the first and second major cutting edges,respectively, and

the first and second cutting bisector lines are mutually offset.

Also, in accordance with the present invention, there is provided aninsert holder and an indexable cutting insert removably retainedtherein,

-   -   the insert holder having a holder head and a holder shank        longitudinally extending in a rearward direction therefrom along        a holder axis,        -   the holder head having a seat surface and spaced apart first            and second male and/or female support elements associated            with the seat surface,            -   the first support element having first and second                support walls transverse to the seat surface,            -   the second support element having a third support wall                transverse to the seat surface,            -   in a cross-section taken in a second horizontal plane                parallel to the seat surface and intersecting the first                and second support elements, first and third imaginary                straight support lines tangential to the first and third                support walls form a support angle of less than 180                degrees,    -   the cutting insert having a central mounting portion and first        and second cutting portions,        -   the central mounting portion having opposing upper and lower            surfaces, an interconnecting peripheral side surface, and an            insert axis passing through the upper and lower surfaces            defining an upward-to-downward direction,            -   the upper surface facing in the upward direction and                having a force application aperture or recess associated                therewith,            -   the lower surface facing in the downward direction and                having spaced apart first and second male and/or female                abutment elements associated therewith,                -   the first abutment element having diverging left and                    right first abutment surfaces transverse to the                    lower surface, which in a cross-section taken in a                    first horizontal plane perpendicular to the insert                    axis and intersecting the first and second abutment                    elements has left and right first imaginary straight                    abutment lines tangential to the left and right                    first abutment surfaces forming a first local                    abutment angle, and a first abutment bisector plane                    parallel to or containing the insert axis bisects                    the first local abutment angle,                -   the second abutment element having diverging left                    and right second abutment surfaces transverse to the                    lower surface, which in a cross-section taken in the                    first horizontal plane has left and right second                    imaginary straight abutment lines tangential to the                    left and right second abutment surfaces forming a                    second local abutment angle, and a second abutment                    bisector plane parallel to or containing the insert                    axis bisects the second local abutment angle,        -   the first and second cutting portions extending away from            the central mounting portion and having distal first and            second major cutting edges, respectively, and the first and            second cutting portions being entirely located in diagonally            opposite imaginary quadrants of four imaginary quadrants            defined by mutually perpendicular first and second quadrant            planes containing the insert axis,            -   each cutting portion having a rake surface adjacent to                its respective major cutting edge facing in the upward                direction,

wherein:

the first and second abutment bisector planes and the first quadrantplane are parallel or coincident,

wherein in each index position of the cutting insert:

only one of the two cutting portions is operative,

the lower surface is in contact with the seat surface,

a clamping member engages the clamping aperture or recess and applies aclamping force thereto,

the left and right first abutment surfaces or the left and right secondabutment surfaces are in contact with the first and second supportwalls, respectively, and

one of the left and right first abutment surfaces or one of the left andright second abutment surfaces is in contact with the third supportwall,

and wherein in a top view of the cutting tool:

at least a point along the operative major cutting edge is located in astable region subtended by the support angle.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding, the invention will now be described, by wayof example only, with reference to the accompanying drawings in whichchain-dash lines represent cut-off boundaries for partial views of amember and in which:

FIG. 1 is a first perspective view of a cutting insert in accordancewith some embodiments of the present invention;

FIG. 2 is a second perspective view of the cutting insert shown in FIG.1;

FIG. 3 is a top view of the cutting insert shown in FIG. 1;

FIG. 4 is a bottom view of the cutting insert shown in FIG. 1;

FIG. 5 is a first side view of the cutting insert shown in FIG. 1;

FIG. 6 is a second side view of the cutting insert shown in FIG. 1;

FIG. 7 is a cross-sectional view of the cutting insert shown in FIG. 5,taken along the line VII-VII;

FIG. 8A is a cross-sectional view of the cutting insert shown in FIG. 4,taken along the line VIIIA-VIIIA;

FIG. 8B is a cross-sectional view of the cutting insert shown in FIG. 4,taken along the line VIIIB-VIIIB;

FIG. 9 is a perspective view of a cutting tool in accordance with someembodiments of the present invention;

FIG. 10 is an exploded perspective view of the cutting tool shown inFIG. 9;

FIG. 11 is a top view of an insert holder shown in FIGS. 9 and 10;

FIG. 12 is a side view of the insert holder shown in FIGS. 9 and 10;

FIG. 13 is a cross-sectional view of the insert holder shown in FIG. 12,taken along the line XIII-XIII;

FIG. 14 is a top view of the cutting tool shown in FIG. 9, with hiddendetail;

FIG. 15 is an exploded perspective view of a cutting tool in accordancewith alternative embodiments of the present invention; and

FIG. 16 is a top view of the cutting tool shown in FIG. 15, with hiddendetail.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1 to 6, one aspect of the present invention relates toan indexable cutting insert 20 having a central mounting portion 22 andfirst and second cutting portions 24 a, 24 b. As seen in FIGS. 3 and 4,in a top or bottom view of the cutting insert 20, the cutting portions24 a, 24 b may project transversely, and in generally oppositedirections, from opposite ends of the central mounting portion 22.

In some embodiments of the present invention, the cutting insert 20 maypreferably be manufactured by form pressing and sintering a cementedcarbide, such as tungsten carbide, and may be coated or uncoated.

The central mounting portion 22 has opposing upper and lower surfaces26, 28, an interconnecting peripheral side surface 30, and an insertaxis AI passing through the upper and lower surfaces 26, 28 defining anupward-to-downward direction DU, DD.

In some embodiments of the present invention, the lower surface 28 maybe planar.

It should be appreciated that use of the term “planar”, throughout thedescription and claims, with respect to the lower surface 28, covers thepossibility of the lower surface 28 having a plurality of spaced apartcoplanar sub-surfaces.

In some embodiments of the present invention, the insert axis AI may beperpendicular to the lower surface 28.

As shown in FIGS. 5 and 6, the upper surface 26 faces in the upwarddirection DU, the lower surface 28 faces in the downward direction DD,and the upper and lower surfaces 26, 28 define an insert thickness TI.

In some embodiments of the present invention, the upper surface 26 mayhave a force application aperture or recess 32 associated therewith.

Also, in some embodiments of the present invention, the forceapplication aperture or recess 32 may be in the form of a clampingthrough bore 34 intersecting the upper and lower surfaces 26, 28.

Further, in some embodiments of the present invention, the clampingthrough bore 34 may be coaxial to the insert axis AI.

As shown in FIGS. 2 and 4, the lower surface 28 has spaced apart firstand second lower abutment elements 36 a, 36 b associated therewith. Eachof the lower abutment elements 36 a, 36 b may be either male or female.

It should be appreciated that use of the term “associated therewith”,throughout the description and claims, with respect to the first andsecond male and/or female abutment elements 36 a, 36 b and the lowersurface 28, covers the possibility of the first and second abutmentelements 36 a, 36 b being male elements disposed on (i.e., protrudingfrom) the lower surface 28, and also the possibility of the plurality ofthe first and second abutment elements 36 a, 36 b being female elementsbeing disposed in (i.e., recessed into) the lower surface 28.

In some embodiments of the present invention, as shown in FIG. 2, thefirst and second abutment elements 36 a, 36 b may be female-typeelements.

Also, in some embodiments of the present invention, the first and secondabutment elements 36 a, 36 b may exhibit rotational symmetry about theinsert axis AI.

As shown in FIG. 4, the first abutment element 36 a has diverging leftand right first abutment surfaces 38 a, 38 b transverse to the lowersurface 28.

Also, as shown in FIG. 4, the second abutment element 36 b has divergingleft and right second abutment surfaces 40 a, 40 b transverse to thelower surface 28.

For embodiments of the present invention, in which the first and secondabutment elements 36 a, 36 b are female-type elements, the left andright first abutment surfaces 38 a, 38 b may diverge away from theinsert axis AI and the left and right second abutment surfaces 40 a, 40b may diverge away from the insert axis AI.

As shown in FIG. 7, in a cross-section taken in a first horizontal planePH1 perpendicular to the insert axis AI and intersecting the first andsecond abutment elements 36 a, 36 b, the first abutment element 36 a hasleft and right first imaginary straight abutment lines L1 a, L1 btangential to the left and right first abutment surfaces 38 a, 38 bforming a first local abutment angle α1.

In some embodiments of the present invention, in a cross-section takenin the first horizontal plane PH1, the left and right first abutmentsurfaces 38 a, 38 b may be linear and coincident with the left and rightfirst imaginary straight abutment lines L1 a, L1 b.

As shown in FIG. 7 in a cross-section taken in the first horizontalplane PH1, the second abutment element 36 b has left and right secondimaginary straight abutment lines L2 a, L2 b tangential to the left andright second abutment surfaces 40 a, 40 b forming a second localabutment angle α2.

In some embodiments of the present invention, in a cross-section takenin the first horizontal plane PH1, the left and right second abutmentsurfaces 40 a, 40 b may be linear and coincident with the left and rightsecond imaginary straight abutment lines L2 a, L2 b.

As shown in FIG. 7, the first and second local abutment angles α1, α2may be acute angles of at least 30 degrees, i.e. α1≥30° and α2≥30°.

In some embodiments of the present invention, the first and second localabutment angles α1, α2 may be equal.

For embodiments of the present invention, in which the first and secondabutment elements 36 a, 36 b are female-type elements, the first andsecond local abutment angles α1, α2 may be external angles.

It should be appreciated that use of the term “external angle”throughout the description and claims refers to an angle associated withtwo surface components as measured external to the member(s) on whichthese surface components are formed.

As shown in FIG. 7, a first abutment bisector plane PB1 containing theinsert axis AI bisects the first local abutment angle α1, and a secondabutment bisector plane PB2 containing the insert axis AI bisects thesecond local abutment angle α2.

In some embodiments of the present invention, the first and secondabutment bisector planes PB1, PB2 may be coincident.

In other embodiments of the present invention (not shown), the first andsecond abutment bisector planes PB1, PB2 may be mutually offset andparallel to the insert axis AI.

As shown in FIG. 8A, in a cross-section taken in a first vertical planePV1 perpendicular to the first abutment bisector plane PB1 andintersecting the first abutment element 36 a, each of the left and rightfirst abutment surfaces 38 a, 38 b may form an obtuse first inclinationangle σ1 with the lower surface 28.

In some embodiments of the present invention, the left and right firstabutment surfaces 38 a, 38 b may each be planar.

As shown in FIG. 8B, in a cross-section taken in a second vertical planePV2 perpendicular to the second abutment bisector plane PB2 andintersecting the second abutment element 36 b, each of the left andright second abutment surfaces 40 a, 40 b may form an obtuse secondinclination angle σ2 with the lower surface 28.

In some embodiments of the present invention, the left and right secondabutment surfaces 40 a, 40 b may each be planar.

For embodiments of the present invention, in which the first and secondabutment elements 36 a, 36 b are female-type elements, the first andsecond inclination angles σ1, σ2 may be internal angles.

It should be appreciated that use of the term “internal angle”throughout the description and claims refers to an angle associated withtwo surface components as measured internal to the member(s) on whichthese surface components are formed.

As shown in FIG. 4, in a bottom view of the cutting insert 20, each ofthe first and second abutment elements 36 a, 36 b may be polygonalshaped.

It should be appreciated throughout the description and claims, that abottom view is taken along the insert axis AI.

In some embodiments of the present invention, in a bottom view of thecutting insert 20, each of the first and second abutment elements 36 a,36 b may be triangular shaped.

In other embodiments of the present invention (not shown), in which thefirst and second abutment elements 36 a, 36 b are male-type elements, ina bottom view of the cutting insert 20, each of the first and secondabutment elements 36 a, 36 b may be rhombus shaped.

Also, in other embodiments of the present invention (not shown), inwhich the first and second abutment elements 36 a, 36 b are male-typeelements, the left and right first abutment surfaces 38 a, 38 b mayconverge away from the insert axis AI and the left and right secondabutment surfaces 40 a, 40 b may converge away from the insert axis AI.

As shown in FIGS. 1 to 4, the first and second cutting portions 24 a, 24b extend away from the central mounting portion 22 and have distal firstand second major cutting edges 42 a, 42 b, respectively.

As shown in FIGS. 5 and 6, each cutting portion 24 a, 24 b has a rakesurface 44 a, 44 b adjacent to its respective major cutting edge 42 a,42 b facing in the upward direction DU.

In some embodiments of the present invention, the first and secondcutting portions 24 a, 24 b may be elongated members integrally formedwith the central mounting portion 22 to have one-piece unitaryconstruction therewith.

Also, in some embodiments of the present invention, the first and secondcutting portions 24 a, 24 b may exhibit rotational symmetry about theinsert axis AI.

As shown in FIG. 3, in a top view of the cutting insert 20, the firstand second cutting portions 24 a, 24 b extend away from the centralmounting portion 22 in opposite first and second directions D1, D2,respectively.

It should be appreciated throughout the description and claims, that atop view is taken along the insert axis AI.

Also, as shown in FIG. 3, in a top view of the cutting insert 20, firstand second cutting bisector lines BL1, BL2 parallel to the first andsecond directions D1, D2 bisect the first and second major cutting edges42 a, 42 b, respectively.

According to the present invention, the first and second cuttingbisector lines BL1, BL2 are mutually offset.

In some embodiments of the present invention, as shown in FIG. 3, in atop view of the cutting insert 20, the first and second major cuttingedges 42 a, 42 b may be entirely located outside a first imaginarycircle C1 containing the central mounting portion 22.

Also, in some embodiments of the present invention, the first imaginarycircle C1 may be coaxial to the insert axis AI.

As shown in FIG. 3, in a top view of the cutting insert 20, the firstand second major cutting edges 42 a, 42 b have first and second cuttingwidths W1, W2 measured perpendicular to the first and second cuttingbisector lines BL1, BL2, respectively.

Also, as shown in FIG. 4, in a bottom view of the cutting insert 20, thefirst and second cutting portions 24 a, 24 b extend first and secondcutting lengths LC1, LC2 in the first and second directions D1, D2,respectively.

In some embodiments of the present invention, the first and secondcutting lengths LC1, LC2 may be greater than the first and secondcutting widths W1, W2, respectively, i.e. LC1>W1 and LC2>W2.

Also, in some embodiments of the present invention, the first and secondcutting lengths LC1, LC2 may be greater than two times the first andsecond cutting widths W1, W2, respectively, i.e. LC1>2*W1 and LC2>2*W2.

It should be appreciated that the first and second cutting portions 24a, 24 b are configured to provide clearance for the first and secondmajor cutting edges 42 a, 42 b along their entire longitudinal extentsduring a cutting operation, i.e. along the entire first and secondcutting lengths LC1, LC2, respectively.

The cutting insert 20 according to the present invention, isparticularly suitable for face grooving and internal groovingoperations, by virtue of the first and second cutting bisector linesBL1, BL2 being mutually offset, and the first and second cutting lengthsLC1, LC2 being greater than the first and second cutting widths W1, W2,respectively.

The cutting insert 20 according to the present invention, is alsosuitable for side grooving, turning and threading operations.

In some embodiments of the present invention, the insert thickness TImay be greater than each of the first and second cutting lengths LC1,LC2, i.e. TI>LC1 and TI>LC2.

Also, in some embodiments of the present invention, the first and secondcutting portions 24 a, 24 b may each have a minimum cutting heightH_(MIN) measured parallel to the insert axis AI.

Further, in some embodiments of the present invention, the minimumcutting height H_(MIN) may be greater than two thirds the insertthickness TI, i.e. H_(MIN)>⅔*TI.

For embodiments of the present invention, in which the insert thicknessTI is greater than each of the first and second cutting lengths LC1,LC2, and the minimum cutting height H_(MIN) is greater than two thirdsthe insert thickness TI, the first and second cutting portions 24 a, 24b may be sufficiently robust so that an underside 45 a, 45 b of eachcutting portion 24 a, 24 b, opposite the respective rake surface 44 a,44 b, does not require support during cutting operations.

According to the present invention, the first and second cuttingportions 24 a, 24 b are entirely located in diagonally oppositeimaginary quadrants Q1, Q3 of four imaginary quadrants Q1, Q2, Q3, Q4defined by mutually perpendicular first and second quadrant planes PQ1,PQ2 containing the insert axis AI.

In addition to containing the insert axis AI, the first quadrant planePQ1 may extend along a long dimension of the central mounting portion22, bisect the central mounting portion 22 and thus be considered alongitudinal insert plane PQ1. Meanwhile, in addition to the containingthe insert axis AI and being perpendicular to the first quadrant planePQ1, the second quadrant plane PQ2 may extend along a short dimension ofthe central mounting portion 22, bisect the central mounting portion 22,and thus be considered a transverse insert plane PQ2.

In some embodiments of the present invention, the first quadrant planePQ1 may be coincident with the first and second abutment bisector planesPB1, PB2.

In other embodiments of the present invention (not shown), the firstquadrant plane PQ1 may be parallel to (and offset from) the first andsecond abutment bisector planes PB1, PB2.

As shown in FIGS. 3 and 4, the first and second directions D1, D2 mayeach form a zero angle with the second quadrant plane PQ2.

In other embodiments of the present invention (not shown), the first andsecond directions D1, D2 may each form an acute angle of less than 30degrees with the second quadrant plane PQ2.

In some embodiments of the present invention, the cutting insert 20 mayhave exactly two cutting portions 24 a, 24 b.

Also, in some embodiments of the present invention, the cutting insert20 may exhibit rotational symmetry about the insert axis AI, and thus beindexable about the insert axis AI.

Further, in some embodiments of the present invention, in a top orbottom view of the cutting insert 20 (FIG. 3 or FIG. 4), the insert mayexhibit mirror anti-symmetry about each of the first and second quadrantplanes PQ1, PQ2.

It should be appreciated that the cutting insert 20 may include visualmarkings to assist an operator when indexing the cutting insert 20. Thevisual markings are not considered to detract from the insert'srotational symmetry about the insert axis AI, or the insert's mirroranti-symmetry about each of the first and second quadrant planes PQ1,PQ2.

As shown in FIG. 3, the peripheral side surface 30 may include first andsecond pairs of opposing side surfaces S1, S2.

In some embodiments of the present invention, the first quadrant planePQ1 may intersect the first pair of side surfaces S1, and the secondquadrant plane PQ2 may intersect the second pair of side surfaces S2.

Also, in some embodiments of the present invention, each major cuttingedge 42 a, 42 b may be entirely located further from the first quadrantplane PQ1 than the second pair of side surfaces S2.

Further, in some embodiments of the present invention, each majorcutting edge 42 a, 42 b may be entirely located further from the firstquadrant plane PQ1 than any part of the central mounting portion 22.

As shown in FIG. 3, in a top view of the cutting insert 20, the firstpair of side surfaces S1 may be parallel and offset by a first distanceDS1, and the second pair of side surfaces S2 may be parallel and offsetby a second distance DS2.

In some embodiments of the present invention, the first distance DS1 maybe greater than the second distance DS2.

Also, in some embodiments of the present invention, in a top view of thecutting insert 20, the first and second pairs of side surfaces S1, S2may define an imaginary rectangle RT.

The first pair of side surfaces S1 may extend along a transverselydirected width dimension of the imaginary rectangle RT while the secondpair of side surfaces S2 may extend along a longitudinally directedlength dimension of the imaginary rectangle RT, the length dimensionbeing longer than the width dimension. Thus, as seen in the top view ofthe cutting insert 20 (FIG. 3), the central mounting portion 22 has arectangular shape which falls within, and nearly fully occupies, therectangular footprint formed by the imaginary rectangle RT.

As shown in FIG. 7, in a cross-section taken in the first horizontalplane PH1, the left first and right second imaginary straight abutmentlines L1 b, L2 a may form a first non-local abutment angle δ1 of lessthan 180 degrees, and the left second and right first imaginary straightabutment lines L2 b, L1 a may form a second non-local abutment angle δ2of less than 180 degrees.

In some embodiments of the present invention, the first and secondnon-local abutment angles δ1, δ2 may be obtuse and equal.

For embodiments of the present invention, in which the first and secondabutment elements 36 a, 36 b are female-type elements, the first andsecond non-local abutment angles δ1, δ2 may be internal angles.

As shown in FIG. 7, at least first and second points N1, N2 along thefirst and second major cutting edges 42 a, 42 b may be located in firstand second regions R1, R2 subtended by the first and second non-localabutment angles δ1, δ2, respectively.

In some embodiments of the present invention, the entire first andsecond major cutting edges 42 a, 42 b may be located in the first andsecond regions R1, R2, respectively.

Also, in some embodiments of the present invention, the first and secondpoints N1, N2 may be the furthest-most points of the first and secondmajor cutting edges 42 a, 42 b, respectively, from the second quadrantplane PQ2.

Further, in some embodiments of the present invention, the first andsecond points N1, N2 may be the furthest-most points of the entirecutting insert 20 from the second quadrant plane PQ2.

It should be appreciated that for embodiments of the present invention,in which the first and second points N1, N2 are the furthest-most pointsof the entire cutting insert 20 from the second quadrant plane PQ2, thecutting insert 20 may be suitable for use in next-to-shoulder cuttingoperations.

As shown in FIGS. 9 to 14, another aspect of the present inventionrelates to a cutting tool 46 having an insert holder 48 and theaforementioned cutting insert 20 removably retained therein.

The insert holder 48 has a holder head 50 and a holder shank 52longitudinally extending in a rearward direction DR therefrom along aholder axis AH.

As shown in FIGS. 10 to 12, the holder head 50 has a seat surface 54 andspaced apart first and second support elements 56, 58 associated withthe seat surface 54. Each of the support elements 56, 58 may be eithermale or female.

It should be appreciated that use of the term “associated with the seatsurface 54”, throughout the description and claims, with respect to thefirst and second male and/or female support elements 56, 58, covers thepossibility of the first and second support elements 56, 58 being maleelements disposed on (i.e., protruding from) the seat surface 54, andalso the possibility of the first and second support elements 56, 58being female elements being disposed in (i.e., recessed into) the seatsurface 54.

In some embodiments of the present invention, as shown in FIGS. 10 and12, the first and second support elements 56, 58 may be male-typeelements.

As shown in FIGS. 10 and 12, the first support element 56 has first andsecond support walls 60, 62 transverse to the seat surface 54, and thesecond support element 58 has a third support wall 64 transverse to theseat surface 54.

In some embodiments of the present invention, the seat surface 54 may beplanar.

It should be appreciated that use of the term “planar”, throughout thedescription and claims, with respect to the seat surface 54, covers thepossibility of the seat surface 54 having a plurality of spaced apartcoplanar sub-surfaces.

In each index position of the cutting insert 20:

only one of the two cutting portions 24 a, 24 b is operative,

the lower surface 28 is in contact with the seat surface 54,

the first and second abutment elements 36 a, 36 b occupy or are occupiedby the first and second support elements 56, 58, and

a clamping member 66 engages the clamping aperture or recess 32 andapplies a clamping force FC thereto.

For embodiments of the present invention, in which the cutting insert 20has exactly two cutting portions 24 a, 24 b, the cutting insert 20 hastwo index positions in the cutting tool 46.

As shown in FIGS. 9 and 10, the clamping member 66 may be in the form ofa clamping screw 68, and the clamping screw 68 may pass through theclamping through bore 34 and threadingly engage a threaded bore 70 inthe seat surface 54.

As shown in FIGS. 10 and 11, the threaded bore 70 has a bore axis AB.

In some embodiments of the present invention, in each index position ofthe cutting insert 20, the insert axis AI may be non-coaxial with thebore axis AB, and the threaded bore 70 may be eccentric in relation tothe clamping through bore 34.

Also, in some embodiments of the present invention, in each indexposition of the cutting insert 20, the clamping force FC may be appliedvia the clamping screw 68 to a distinct circumferential portion of theclamping through bore 34.

For embodiments of the present invention, in which the cutting insert 20has two index positions in the cutting tool 46, the clamping throughbore 34 may have two distinct circumferential portions against which theclamping force FC is applied.

As shown in FIG. 14, in each index position of the cutting insert 20,the clamping force FC may be directed transverse to the first quadrantplane PQ1 and away from the two imaginary quadrants Q1, Q4; Q2, Q3located on the same side of the first quadrant plane PQ1 as theoperative cutting portion 24 a, 24 b.

Also, as shown in FIG. 14, in each index position of the cutting insert20, the first and second support elements 56, 58 may be located onopposite sides of the second quadrant plane PQ2.

In some embodiments of the present invention, the first support element56 may be located on the same side of the second quadrant plane PQ2 asthe non-operative cutting portion 24 a, 24 b, and the second supportelement 58 may be located on the same side of the second quadrant planePQ2 as the operative cutting portion 24 a, 24 b.

Also, in some embodiments of the present invention, as shown in FIGS. 10to 14, the second support element 58 may be proximate the free end(i.e., the end remote from the holder shank 52) of the seat surface 54.

Further, in some embodiments of the present invention, the clampingforce FC may be directed away from the imaginary quadrant Q1, Q3containing the operative cutting portion 24 a, 24 b and towards theimaginary quadrant Q1, Q3 containing the non-operative cutting portion24 a, 24 b.

As shown in FIG. 13, in a cross-section taken in a second horizontalplane PH2 parallel to the seat surface 54 and intersecting the first andsecond support elements 56, 58, first and third imaginary straightsupport lines LS1, LS3 tangential to the first and third support walls60, 64 form a support angle π of less than 180 degrees.

In some embodiments of the present invention, the support angle π may bean obtuse angle of at most 150 degrees, i.e. 90°<π≤150°.

For embodiments of the present invention, in which the first and secondsupport elements 56, 58 are male-type elements, the support angle π maybe an external angle.

The support angle π subtends a stable region RS, and when cutting forcesacting on the cutting insert 20 occur at points or zones inside thestable region RS, the cutting insert 20 is removably retained in theinsert holder 48 with a high level of stability.

In some embodiments of the present invention, the support angle π may besubstantially equal to the first and second non-local abutment anglesδ1, δ2.

Also, in some embodiments of the present invention, the first and secondhorizontal planes PH1, PH2 may be coincidental.

As shown in FIG. 14, in each index position of the cutting insert 20:

the left and right first abutment surfaces 38 a, 38 b or the left andright second abutment surfaces 40 a, 40 b are in contact with the firstand second support walls 60, 62, respectively, and

one of the left and right first abutment surfaces 38 a, 38 b or one ofthe left and right second abutment surfaces 40 a, 40 b is in contactwith the third support wall 64.

It should be appreciated that in each index position of the cuttinginsert 20, apart from the third support wall 64, no surface of thesecond support element 58 transverse to the seat surface 54 may be incontact with any surface of the cutting insert 20.

It should also be appreciated that for embodiments of the presentinvention, in which the clamping force FC is directed towards theimaginary quadrant Q1, Q3 containing the non-operative cutting portion24 a, 24 b, the above-described ‘three-point’ contact between three ofthe insert's four abutment surfaces 38 a, 38 b; 40 a, 40 b and thefirst, second and third support walls 60, 62, 64 is ensured.

For embodiments of the present invention, in which the first and secondabutment elements 36 a, 36 b are female-type elements and the first andsecond support elements 56, 58 are male-type elements, in each indexposition of the cutting insert 20, the right first abutment surface 38 bor the right second abutment surface 40 b may be in contact with thethird support wall 64.

According to the present invention, in a top view of the cutting tool46, as shown in FIG. 14, at least a point along the operative majorcutting edge 42 a, 42 b is located in the stable region RS.

It should be appreciated that having at least a point along theoperative major cutting edge 42 a, 42 b located in the stable region RSprovides optimum stability for the cutting insert 20 against cuttingforces from a range of directions, including, as shown in FIG. 14, afirst cutting force F1 directed perpendicular to and towards the firstquadrant plane PQ1, a second cutting force F2 directed at an angletowards the first quadrant plane PQ1 and away from the second quadrantplane PQ2, and a third cutting force F3 directed perpendicular to andtowards the second quadrant plane PQ2.

In some embodiments of the present invention, the entire operative majorcutting edge 42 a, 42 b may be located in the stable region RS.

It should be appreciated throughout the description and claims, that atop view of the cutting tool 46 is taken perpendicular to the seatsurface 54.

Also, in a top view of the cutting tool 46, as shown in FIG. 14, thefirst and second directions D1, D2 may be perpendicular to the holderaxis AH.

For embodiments of the present invention, in which the first and seconddirections D1, D2 are perpendicular to the holder axis AH, the cuttingtool 46 may be particularly suitable for face grooving and internalgrooving operations.

In other embodiments of the present invention (not shown), the first andsecond directions D1, D2 may be parallel to the holder axis AH.

In some embodiments of the present invention, no surface of theoperative cutting portion 24 a, 24 b may be in contact with the holderhead 50.

Also, in some embodiments of the present invention, as shown in FIG. 14,in a top view of the cutting tool 46, the operative cutting portion 24a, 24 b may extend beyond the peripheral envelope of the holder head 50.

For embodiments of the present invention, in which no surface of theoperative cutting portion 24 a, 24 b is in contact with the holder head50, for example, when the insert's first and second cutting portions 24a, 24 b are sufficiently robust, the holder head 50 may be devoid of anoutwardly protruding auxiliary base member to support the operativecutting portion, and thus the insert holder 48 may be manufactured moreefficiently and cost-effectively.

In each index position of the cutting insert 20, apart from the first,second and third support walls 60, 62, 64 of the first and secondsupport elements 56, 58, no surface of the holder head 50 transverse tothe seat surface 54 may be in contact with any surface of the cuttinginsert 20.

Also, in each index position of the cutting insert 20, no portion of theinsert's peripheral side surface 30 may be in contact with the holderhead 50, and thus the holder head 50 may be devoid of any peripheralsupport walls.

For embodiments of the present invention, in which the holder head 50 isdevoid of any peripheral support walls, the holder head 50 may have areduced compact size, making the cutting tool 46 particularly suitablefor cutting operations in which there is limited access to a rotatingworkpiece, for example, in face grooving and internal groovingoperations.

In alternative embodiments of the present invention, the holder head 150may have a head projection 172 adjacent to the seat surface 154, whichhead projection 172 does not contact any surface of the cutting insert120, but which provides a means for directing a cooling medium towardsthe operative major cutting edge 142 a, 142 b.

It should be appreciated that apart from the additional featuresspecifically associated with alternative embodiments of the invention,having reference numerals greater than 100, the description and claimsis applicable to some embodiments and to alternative embodiments of thepresent invention.

As shown in FIGS. 15 and 16, the means for directing a cooling mediumtowards the operative major cutting edge 142 a, 142 b may be in the formof a fluid delivery head 174 mounted on the head projection 172.

In other embodiments of the invention (not shown), the means fordirecting a cooling medium towards the operative major cutting edge 142a, 142 b may be in the form of a cooling duct and cooling opening in thehead projection 172.

In alternative embodiments of the present invention, the insert's uppersurface 126 may have first and second cooling grooves 176 a, 176 b, andin a top view of the cutting insert 120, the first and second coolinggrooves 176 a, 176 b may extend along the first and second cuttingbisector lines BL1, BL2, respectively.

Also, in alternative embodiments of the present invention, the fluiddelivery head 174 may be configured to direct a cooling medium to theoperative major cutting edge 142 a, 142 b via the respective first orsecond cooling groove 176 a, 176 b.

Although the present invention has been described to a certain degree ofparticularity, it should be understood that various alterations andmodifications could be made without departing from the spirit or scopeof the invention as hereinafter claimed.

What is claimed is:
 1. An indexable cutting insert (20, 120),comprising: a central mounting portion (22) and first and second cuttingportions (24 a, 24 b), the central mounting portion (22) having opposingupper and lower surfaces (26, 126; 28), an interconnecting peripheralside surface (30), and an insert axis (AI) passing through the upper andlower surfaces (26, 126; 28) defining an upward-to-downward direction(DU, DD), the upper surface (26, 126) facing in the upward direction(DU), the lower surface (28) facing in the downward direction (DD) andhaving spaced apart first and second male and/or female abutmentelements (36 a, 36 b) associated therewith, the first abutment element(36 a) having diverging left and right first abutment surfaces (38 a, 38b) transverse to the lower surface (28), which in a cross-section takenin a first horizontal plane (PH1) perpendicular to the insert axis (AI)and intersecting the first and second abutment elements (36 a, 36 b) hasleft and right first imaginary straight abutment lines (L1 a, L1 b)tangential to the left and right first abutment surfaces (38 a, 38 b)forming a first local abutment angle (α1), and a first abutment bisectorplane (PB1) parallel to or containing the insert axis (AI) bisects thefirst local abutment angle (α1), the second abutment element (36 b)having diverging left and right second abutment surfaces (40 a, 40 b)transverse to the lower surface (28), which in a cross-section taken inthe first horizontal plane (PH1) has left and right second imaginarystraight abutment lines (L2 a, L2 b) tangential to the left and rightsecond abutment surfaces (40 a, 40 b) forming a second local abutmentangle (α2), and a second abutment bisector plane (PB2) parallel to orcontaining the insert axis (AI) bisects the second local abutment angle(α2), the first and second cutting portions (24 a, 24 b) extending awayfrom the central mounting portion (22) and having distal first andsecond major cutting edges (42 a, 42 b; 142 a, 142 b), respectively, andthe first and second cutting portions (24 a, 24 b) being entirelylocated in diagonally opposite imaginary quadrants (Q1, Q3) of fourimaginary quadrants (Q1, Q2, Q3, Q4) defined by mutually perpendicularfirst and second quadrant planes (PQ1, PQ2) containing the insert axis(AI), each cutting portion (24 a, 24 b) having a rake surface (44 a, 44b) adjacent to its respective major cutting edge (42 a, 42 b; 142 a, 142b) facing in the upward direction (DU), wherein: the first and secondabutment bisector planes (PB1, PB2) and the first quadrant plane (PQ1)are parallel or coincident, and wherein in a top view of the cuttinginsert (20, 120): the first and second cutting portions (24 a, 24 b)extend away from the central mounting portion (22) in opposite first andsecond directions (D1, D2), respectively, first and second cuttingbisector lines (BL1, BL2) parallel to the first and second directions(D1, D2) bisect the first and second major cutting edges (42 a, 42 b;142 a, 142 b), respectively, and the first and second cutting bisectorlines (BL1, BL2) are mutually offset.
 2. The cutting insert (20, 120)according to claim 1, wherein: the first and second directions (D1, D2)each form a zero or acute angle of less than 30 degrees with the secondquadrant plane (PQ2).
 3. The cutting insert (20, 120) according to claim1, wherein the cutting insert (20, 120) has exactly two cutting portions(24 a, 24 b).
 4. The cutting insert (20, 120) according to claim 1,wherein the first and second abutment elements (36 a, 36 b) exhibitrotational symmetry about the insert axis (AI).
 5. The cutting insert(20, 120) according to claim 1, wherein the upper surface (26, 126) hasa force application aperture or recess (32) associated therewith.
 6. Thecutting insert (20, 120) according to claim 5, wherein the forceapplication aperture or recess (32) is in the form of a clamping throughbore (34) intersecting the upper and lower surfaces (26, 126; 28). 7.The cutting insert (20, 120) according to claim 1, wherein the first andsecond abutment bisector planes (PB1, PB2) are coincident.
 8. Thecutting insert (20, 120) according to claim 1, wherein the first andsecond local abutment angles (α1, α2) are acute angles of at least 30degrees.
 9. The cutting insert (20, 120) according to claim 1, whereinthe first and second abutment elements (36 a, 36 b) are female-typeelements.
 10. The cutting insert (20, 120) according to claim 1, whereinthe first and second cutting portions (24 a, 24 b) are elongated membersintegrally formed with the central mounting portion (22) to haveone-piece unitary construction therewith.
 11. The cutting insert (20,120) according to claim 1, wherein in a cross-section taken in the firsthorizontal plane (PH1): the left first and right second imaginarystraight abutment lines (L1 b, L2 a) form a first non-local abutmentangle (δ1) of less than 180 degrees, and the left second and right firstimaginary straight abutment lines (L2 b, L1 a) form a second non-localabutment angle (δ2) of less than 180 degrees, and wherein: at leastfirst and second points (N1, N2) along the first and second majorcutting edges (42 a, 42 b; 142 a, 142 b) are located in first and secondregions (R1, R2) subtended by the first and second non-local abutmentangles (δ1, δ2), respectively.
 12. The cutting insert (20, 120)according to claim 11, wherein: the entire first and second majorcutting edges (42 a, 42 b; 142 a, 142 b) are located in the first andsecond regions (R1, R2), respectively.
 13. The cutting insert (20, 120)according to claim 1, wherein: the first and second major cutting edges(42 a, 42 b; 142 a, 142 b) have first and second cutting widths (W1, W2)measured perpendicular to the first and second cutting bisector lines(BL1, BL2), respectively, the first and second cutting portions (24 a,24 b) extend first and second cutting lengths (LC1, LC2) in the firstand second directions (D1, D2), respectively, and the first and secondcutting lengths (LC1, LC2) are greater than the first and second cuttingwidths (W1, W2), respectively.
 14. The cutting insert (20, 120)according to claim 13, wherein: the first and second cutting lengths(LC1, LC2) are greater than two times the first and second cuttingwidths (W1, W2), respectively.
 15. The cutting insert (20, 120)according to claim 1, wherein in a top view of the cutting insert (20,120): the first and second major cutting edges (42 a, 42 b; 142 a, 142b) are entirely located outside a first imaginary circle (C1) containingthe central mounting portion (22).
 16. The cutting insert (20, 120)according to claim 1, wherein the peripheral side surface (30) includesfirst and second pairs of opposing side surfaces (S1, S2).
 17. Thecutting insert (20, 120) according to claim 16, wherein: the firstquadrant plane (PQ1) intersects the first pair of side surfaces (S1),and the second quadrant plane (PQ2) intersects the second pair of sidesurfaces (S2).
 18. The cutting insert (20, 120) according to claim 16,wherein each major cutting edge (42 a, 42 b; 142 a, 142 b) is entirelylocated further from the first quadrant plane (PQ1) than the second pairof side surfaces (S2).
 19. A cutting tool (46) comprising: an insertholder (48) and an indexable cutting insert (20, 120) removably retainedtherein, the insert holder (48) having a holder head (50, 150) and aholder shank (52) longitudinally extending in a rearward direction (DR)therefrom along a holder axis (AH), the holder head (50, 150) having aseat surface (54, 154) and spaced apart first and second male and/orfemale support elements (56, 58) associated with the seat surface (54,154), the first support element (56) having first and second supportwalls (60, 62) transverse to the seat surface (54, 154), the secondsupport element (58) having a third support wall (64) transverse to theseat surface (54, 154), in a cross-section taken in a second horizontalplane (PH2) parallel to the seat surface (54, 154) and intersecting thefirst and second support elements (56, 58), first and third imaginarystraight support lines (LS1, LS3) tangential to the first and thirdsupport walls (60, 64) form a support angle (π) of less than 180degrees, the cutting insert (20, 120) having a central mounting portion(22) and first and second cutting portions (24 a, 24 b), the centralmounting portion (22) having opposing upper and lower surfaces (26, 126;28), an interconnecting peripheral side surface (30), and an insert axis(AI) passing through the upper and lower surfaces (26, 126; 28) definingan upward-to-downward direction (DU, DD), the upper surface (26, 126)facing in the upward direction (DU) and having a force applicationaperture or recess (32) associated therewith, the lower surface (28)facing in the downward direction (DD) and having spaced apart first andsecond male and/or female abutment elements (36 a, 36 b) associatedtherewith,  the first abutment element (36 a) having diverging left andright first abutment surfaces (38 a, 38 b) transverse to the lowersurface (28), which in a cross-section taken in a first horizontal plane(PH1) perpendicular to the insert axis (AI) and intersecting the firstand second abutment elements (36 a, 36 b) has left and right firstimaginary straight abutment lines (L1 a, L1 b) tangential to the leftand right first abutment surfaces (38 a, 38 b) forming a first localabutment angle (α1), and a first abutment bisector plane (PB1) parallelto or containing the insert axis (AI) bisects the first local abutmentangle (α1),  the second abutment element (36 b) having diverging leftand right second abutment surfaces (40 a, 40 b) transverse to the lowersurface (28), which in a cross-section taken in the first horizontalplane (PH1) has left and right second imaginary straight abutment lines(L2 a, L2 b) tangential to the left and right second abutment surfaces(40 a, 40 b) forming a second local abutment angle (α2), and a secondabutment bisector plane (PB2) parallel to or containing the insert axis(AI) bisects the second local abutment angle (α2), the first and secondcutting portions (24 a, 24 b) extending away from the central mountingportion (22) and having distal first and second major cutting edges (42a, 42 b; 142 a, 142 b), respectively, and the first and second cuttingportions (24 a, 24 b) being entirely located in diagonally oppositeimaginary quadrants (Q1, Q3) of four imaginary quadrants (Q1, Q2, Q3,Q4) defined by mutually perpendicular first and second quadrant planes(PQ1, PQ2) containing the insert axis (AI), each cutting portion (24 a,24 b) having a rake surface (44 a, 44 b) adjacent to its respectivemajor cutting edge (42 a, 42 b; 142 a, 142 b) facing in the upwarddirection (DU), wherein: the first and second abutment bisector planes(PB1, PB2) and the first quadrant plane (PQ1) are parallel orcoincident, wherein in each index position of the cutting insert (20,120): only one of the two cutting portions (24 a, 24 b) is operative,the lower surface (28) is in contact with the seat surface (54, 154), aclamping member (66) engages the clamping aperture or recess (32) andapplies a clamping force (FC) thereto, the left and right first abutmentsurfaces (38 a, 38 b) or the left and right second abutment surfaces (40a, 40 b) are in contact with the first and second support walls (60,62), respectively, and one of the left and right first abutment surfaces(38 a, 38 b) or one of the left and right second abutment surfaces (40a, 40 b) is in contact with the third support wall (64), and wherein ina top view of the cutting tool (46): at least a point along theoperative major cutting edge (42 a, 42 b; 142 a, 142 b) is located in astable region (RS) subtended by the support angle (π).
 20. The cuttingtool (46) according to claim 19, wherein in a top view of the cuttingtool (46): the first and second cutting portions (24 a, 24 b) extendaway from the central mounting portion (22) in opposite first and seconddirections (D1, D2), respectively, and the first and second directions(D1, D2) are both either parallel to the holder axis (AH) orperpendicular to the holder axis (AH).
 21. The cutting tool (46)according to claim 19, wherein the force application aperture or recess(32) is in the form of a clamping through bore (34) intersecting theinsert's upper and lower surfaces (26, 126; 28).
 22. The cutting tool(46) according to claim 21, wherein: the clamping member (66) is in theform of a clamping screw (68), and the clamping screw (68) passesthrough the clamping through bore (34) and threadingly engages athreaded bore (70) in the seat surface (54, 154).
 23. The cutting tool(46) according to claim 19, wherein in each index position of thecutting insert (20, 120): the first support element (56) may be locatedon the same side of the second quadrant plane (PQ2) as the non-operativecutting portion (24 a, 24 b), and the second support element (58) may belocated on the same side of the second quadrant plane (PQ2) as theoperative cutting portion (24 a, 24 b).
 24. The cutting tool (46)according to claim 21, wherein in each index position of the cuttinginsert (20, 120): the clamping force (FC) is directed transverse to thefirst quadrant plane (PQ1) and away from the two imaginary quadrants(Q1, Q4; Q2, Q3) located on the same side of the first quadrant plane(PQ1) as the operative cutting portion (24 a, 24 b).
 25. The cuttingtool (46) according to claim 21, wherein in each index position of thecutting insert (20, 120): apart from the first, second and third supportwalls (60, 62, 64) of the first and second support elements (56, 58), nosurface of the holder head (50, 150) transverse to the seat surface (54,154) is in contact with any surface of the cutting insert (20, 120).